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Laboratory for Atmospheric and Space Physics

System Overview

CSSWE, like most satellites, is a collection of subsystems. In order to organize the subsystems, the requirements flow-down is defined throughout the mission development, bolstered by mass, power, data, and link budgets, as well as a risk analysis. A 3U CubeSat is defined as a small volume (10cm x 10cm x 30cm), small mass (≤4kg), and completely autonomous (i.e. power, communications) satellite. The CSSWE architecture reflects the “keep it simple” method of satellite development; the system design was simplified to meet requirements rather than designed to “push the envelope.” Two microcontrollers (MCUs) are present in the system, and two subsystems (attitude control system & thermal) are almost entirely passive. The command & data handling (C&DH) board and communication (COMM) radio are commercial off the shelf (COTS) purchases in an effort to minimize risk.



The Colorado Student Space Weather Experiment (CSSWE) is an NSF-funded 3U CubeSat (30×10×10 cm) which houses an energetic particle telescope. The Relativistic Electron and Proton Telescope integrated little experiment (REPTile) will provide directional differential flux measurements of high-energy electrons and protons. The CSSWE mission goals are:

  • Develop a student-designed CubeSat system for space weather investigation
  • Understand the relationships between solar energetic protons (SEPs), flares, and coronal mass ejections (CMEs)
  • Characterize the variations of the Earth’s radiation belt electrons

CSSWE was designed, built, and tested as part of a graduate project within the Department of Aerospace Engineering Sciences at the University of Colorado Boulder. It was delivered January 2012, and launched on September 13, 2012 out of Vandenberg Air Force Base as part of the NASA ELaNa VI launch.

Science Background

Satellites have become increasingly important for global communications, navigation (GPS), and scientific investigations. However, these electronic systems are vulnerable to attack from the environment in which they operate. Solar wind, solar flares, and coronal mass ejections (CMEs) emit charged particles and electromagnetic (EM) radiation which directly impact the Earth and its magnetosphere. Relativistic electrons (100s keV to multiple MeV) emitted by the Sun become trapped in Earth’s outer radiation belt; such electrons are harmful to spacecraft subsystems and astronauts alike, and are appropriately dubbed “killer electrons.” However, the process by which electrons enter and exit the outer radiation belt is not fully understood. Furthermore, CMEs and some solar flares produce high-energy solar energetic protons (SEPs), which are harmful to astronauts. By sensing the directional flux and energy of both relativistic electrons and protons, a connection may be drawn between solar events (flares and CMEs), outer radiation belt evolution, and SEPs. Understanding the coupled dynamics of these events is crucial to determining the effect of solar activity on the satellite systems and developing strategies for predicting and mitigating the impacts.

Both NASA and NSF have realized the impact of these particles and the need to investigate Earth-Sun interactions. The Laboratory for Atmospheric and Space Physics (LASP) located in Boulder, CO, is developing the Relativistic Electron and Proton Telescope (REPT) for inclusion on the NASA Radiation Belt Storm Probes (RBSP) mission, which will measure directional differential flux of particles in the heart of the outer radiation belt. Meanwhile, NSF has developed a call for CubeSat-based Science Missions for Space Weather Research. Since spring 2008, the University of Colorado has been working to miniaturize the REPT particle telescope to fit within the size and power constraints of the CubeSat form factor. Now developed, this miniaturized sensor can be included on any CubeSat to complement the science of RBSP, to aid in understanding high-energy particles, and to understand the impact of these particles on our important national space assets.